Kinetics of channelized membrane ions in magnetic fields

Abstract

The cyclotron resonance model for channel ion transport in weak magnetic fields is extended to include damping losses. The conductivity tensor is obtained for different electric field configurations, including the circuital field E phi normal to the channel axis. The conductivity behavior close to the cyclotron resonance frequency omega c is compared to existing Ca2+-efflux data in the literature. A collision time of .023 s results from this comparison under the assumption that K+ ions are transiting in a 0.35 G field. We estimate a mean kinetic energy of 3.5 eV for this ion at resonance. This model leads to discrete modes of vibration (eigenfrequencies) in the ion-lattice interaction, such that omega n = n omega c. The presence of such harmonics is compatible with recent results by Blackman et al. [1985b] and McLeod et al. [1986] with the interesting exception that even modes do not appear in their observations, whereas the present model has no restriction on n. This harmonic formalism is also consistent with another reported phenomenon, that of quantized multiple conductances in single patch-clamped channels.

AI evidence extraction

Main findings

A cyclotron resonance model for channel ion transport in weak magnetic fields was extended to include damping losses and used to derive conductivity tensors for different electric-field configurations. Model behavior near the cyclotron resonance frequency was compared to existing Ca2+ efflux data; under an assumption of K+ ions transiting in a 0.35 G field, a collision time of 0.023 s was obtained and a mean kinetic energy of 3.5 eV at resonance was estimated. The model predicts discrete vibrational modes (harmonics) with eigenfrequencies ωn = nωc, stated to be compatible with some prior observations, though noting an exception regarding absence of even modes in those observations.

Outcomes measured

• ion transport/channel conductivity (theoretical)
• cyclotron resonance behavior near ωc
• Ca2+ efflux (comparison to literature data)
• quantized multiple conductances in patch-clamped channels (consistency with reported phenomenon)

Limitations

• The work is a theoretical/modeling extension; no new experimental exposure/outcome data are reported in the abstract.
• Comparison to Ca2+ efflux data depends on an explicit assumption (K+ ions transiting in a 0.35 G field).
• Details of the referenced literature data and the comparison method are not provided in the abstract.

{
    "study_type": "other",
    "exposure": {
        "band": "ELF",
        "source": "other",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": null
    },
    "population": null,
    "sample_size": null,
    "outcomes": [
        "ion transport/channel conductivity (theoretical)",
        "cyclotron resonance behavior near ωc",
        "Ca2+ efflux (comparison to literature data)",
        "quantized multiple conductances in patch-clamped channels (consistency with reported phenomenon)"
    ],
    "main_findings": "A cyclotron resonance model for channel ion transport in weak magnetic fields was extended to include damping losses and used to derive conductivity tensors for different electric-field configurations. Model behavior near the cyclotron resonance frequency was compared to existing Ca2+ efflux data; under an assumption of K+ ions transiting in a 0.35 G field, a collision time of 0.023 s was obtained and a mean kinetic energy of 3.5 eV at resonance was estimated. The model predicts discrete vibrational modes (harmonics) with eigenfrequencies ωn = nωc, stated to be compatible with some prior observations, though noting an exception regarding absence of even modes in those observations.",
    "effect_direction": "unclear",
    "limitations": [
        "The work is a theoretical/modeling extension; no new experimental exposure/outcome data are reported in the abstract.",
        "Comparison to Ca2+ efflux data depends on an explicit assumption (K+ ions transiting in a 0.35 G field).",
        "Details of the referenced literature data and the comparison method are not provided in the abstract."
    ],
    "evidence_strength": "insufficient",
    "confidence": 0.7399999999999999911182158029987476766109466552734375,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "cyclotron resonance",
        "ion transport",
        "membrane channels",
        "damping losses",
        "conductivity tensor",
        "weak magnetic fields",
        "Ca2+ efflux",
        "K+ ions",
        "harmonics",
        "eigenfrequencies",
        "patch clamp"
    ],
    "suggested_hubs": []
}

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